Muffler or silencer



June 9, 1942. c. L. MERETT MUFFLER OR SILENCER Filed Aug. 20, 1941 2 Sheets-Sheet 1 June 9, 1942. c, MERETT 2,285,674

MUFFLER OR SILENCER Filed Aug. 20, 1941 2 Sheets-Sheet 2 Cil'J'fere 1 %7%mwi/ w latented .Iune 9, 1942 UNITED STATES PATENT OFFICE MUFFLER R SILENCER Cecil L. Mcrett, Tulsa, Okla.

Application August 20, 1941, Serial No. 407,652

1 Claim.

This invention relates to mulliers or silencers for the exhaust of internal combustion engines and is especially adapted for aeroplanes and other types of aircraft and also may be successfully employed on land vehicles as well as on marine vehicles.

The primary object of this invention is the provision of a muiller or silencer which will be durable, economical to construct and install and will reduce exhaust sound and back pressure on an engine to a minimum.

Another object of this invention is the provision of a device of the above stated character which operates on a partial vacuum principle to assist in the escape of the exhaust therefrom and thereby reduce to a minimum back pressure on the engine and also includes means for freeing the exhaust therefrom when the engine is idling or the aeroplane or vehicle is not in motion, to prevent overloading of the device with exhaust at a time when the vacuum principle will be inoperative.

With these and other objects in view as will become more apparent as the description proceeds, the invention consists in certain novel features of construction, combination and arrangement of parts as will be hereinafter more fully described and claimed.

For a complete understanding of my invention, reference is to be had to the following description and accompanying drawings, in which Figure 1 is a side elevation, partly in section, illustrating a muiiler or silencer constructed in accordance with my invention.

Figure 2 is a vertical sectional view illustrating the device.

Figure 3 is a transverse sectional view taken on the line 3-3 of Figure 2.

Figure 4 is a transverse sectional view taken on the line 4-4 of Figure 1.

Figure 5 is a transverse sectional view taken on the line 5-5 of Figure 1.

Referring in detail to the drawings, the numeral 5 indicates an elongated exhaust chamber, having an exhaust receiving end A and a wall end B provided with a port in which is secured a tail pipe 6. The exhaust chamber 5 is of tubular formation and the exhaust receiving end A thereof is adapted to be connected in any suitable way to an exhaust pipe of an internal combustion engine.

The exhaust chamber 5 is provided with groups of ports I and 8 spaced a selected distance apart. The ports of each group are arranged in annular formation. Arranged within the exhaust chamber 5 between the groups of ports 1 and 8 is a perforated bafiie 9 in the form of a disc. Arranged slightly in advance or toward the end A of the chamber 5 with respect to the group of ports I is a substantially conical shaped perforated baifie II], the apex of which is disposed toward the exhaust receiving end A of the chamv ber.

A ballie ll constructed and shaped similar to the baffle I0 is arranged between the baffle 9 and the group of ports 8 within the chamber 5 with the apex thereof disposed toward the tail pipe 6.

The battle l0 acts to check the flow of exhaust received from the exhaust chamber 5 by way of the receiving end A before reaching the group of ports I and that exhaust which fails to escape from the chamber 5 by way of the ports I is again checked in its flow by the bafiie 9 as well as the baffle ll before reaching the group of ports 8.

An air tunnel l2 surrounds the major portion of the exhaust chamber 5 and is spaced therefrom covering the groups of ports 'I and 8. The air receiving end of the tunnel I2 is flared or substantially conical shaped, as shown at I3, and is adapted to be arranged in the direction of movement of the vehicle, aeroplane or the like and is preferably located so that air will be driven therein by either the cooling fan of the internal combustion engine or the propeller of the air vehicle. The opposite end of the air tunnel i2 is fully open and terminates a limited distance beyond the end B of the exhaust chamber.

Venturi units l4 and I5 are arranged within the space occurring between the exhaust chamber 5 and the air tunnel l2 and about the groups of ports 1 and 8.

Each Venturi unit includes inner and outer substantially conical shaped sleeves I6 and I1 coactive in defining a Venturi passage l8.

Any suitable web construction may be provided between the sleeves l6 and IT. for joining said sleeves in a unit and it is to be understood that the outer sleeves I! are secured on the walls of the air tunnel l2 while the inner sleeves l6 are secured on the walls of the exhaust cham ber 5.

The Venturi units l4 and I5 act to increase the velocity of flow of air in the air tunnel l2 past the groups of ports I and 8 creating a partial vacuum within the inner sleeves iii of said Venturi units. This partial vacuum acts to draw exhaust gases from the exhaust chamber 5 into the air tunnel for escape at the open end thereof along with the flow of air causing a substantially complete deadening oi exhaust sound, also assisting in the substantially free flow oi the exhaust gases from the exhaust chamber to eliminate as near as possible back pressure upon the engine.

A gravity actuated self-closing check valve 20 is arranged in the tail pipe 8 adjacent where the latter secures in the ported wall of the end B 01' theexhaust chamber. The partial vacuum acting in the exhaust chamber assists in closing the check valve 20, consequently under normal operating conditions exhaust is prevented from escaping through the tailpipe from the exhaust chamber. These normal conditions are when the air vehicle or other type of vehicle is in motion or air is being driven through the air tunnel either by the cooling fan of the engine or the propeller. However, when the engine is operating at idling speed or when the vehicle is in non-motion the check valve 20 being closed will open under a slight amount of exhaust pressure in the exhaust chamber 5 and permit the exhaust to escape by way of the tail pipe 6 for the purpose of preventing undue back pressure on the engine at this time and also to eliminate overloading of the device with exhaust gases at said period of time.

A muiiier or silencer constructed in accordance with the foregoing description and clearly shown in the accompanying drawings can be economically manufactured and installed on an internal combustion engine and will efliciently silence to a minimum exhaust sound and owing to its particular construction and operation back pressure on the engine will be reduced to a minimum.

While I have shown and described the preferred embodiment ot my invention, it will be understood that minor changes in construction, combination and arrangement of parts may be made without departing from the spirit andscope oi the invention as claimed.

Having thus described the invention, what I claim is:

In an exhaust silencer, a tubular exhaust chamber having an exhaust receiving end and an exhaust escape end, a check valve in said escape end of the chamber to resist the escape oi the exhaust therefrom and adapted to open under pressure to permit escape of exhaust when the exhaust in the chamber tends to materially retard incoming exhaust therethrough, an air drum surrounding the chamber and adapted to convey an annular stream of air about the chamber and toward the escape end of said chamber, said chamber having an annular group of ports for admitting exhaust from said chamber into the drum, a conical shaped perforated baflle arranged in the chamber between the ports and the receiving end of said chamber with the apex end thereof disposed toward said receiving end, a second baflle in the chamber between the ports and the escape end of the chamber, and a Venturi unit arranged in the drum and including spaced nested substantially conical shaped sleeves surrounding the ports and spaced therefrom and one of said sleeves being sealed to the drum and the other sleeve being sealed to the chamber between the ports and the receiving end of said chamber, said Venturi unit acting to increase the flow of air of the air stream in the drum to create a suction within one of the sleeves to assist the flow of exhaust through the ports for mixing with the air stream and the discharge thereof along with the air of the air stream to the atmosphere from the end of the drum adjacent the escape end of the chamber.

CECIL L. MERETT. 

